People communicate wirelessly and on the go. Among the devices that make this possible are those sometimes referred to as personal mobile devices. Examples of personal mobile devices include cell phones, smartphones, walkie-talkies, and portable hotspots, among others. A personal mobile device may be handheld (as may be the case for a walkie-talkie), body-mounted, or attached to a vehicle (such as the roof of a car), as examples.
Given the relative ease with which radio signals can be intercepted, communication with (or between) personal mobile devices is often encrypted to prevent interception of the communication by third parties. In voice communication, encryption is used to convert voice data into unintelligible data, while decryption is the process of converting the unintelligible data back to the original voice data, which can then be used to generate audible voice. The respective algorithms used for encryption and decryption are often referred to collectively as a cipher. Examples of common ciphers include Advanced Encryption Standard (AES), Blowfish, Triple Data Encryption Algorithm (3DES), and RC4, among numerous others.
Many devices communicate locally using Bluetooth protocols. Bluetooth is a standardized communication protocol for exchanging data over a short distance between devices. Typically, Bluetooth utilizes a band of frequencies between 2.4-2.485 GHz. Many communication profiles have been developed for Bluetooth, including Advanced Audio Distribution Profile (A2DP), Audio/Video Remote Control Profile (AVRCP), File Transfer Profile (FTP), Hands-Free Profile (HFP), Headset Profile (HSP), Personal Area Networking (PAN) Profile, as well as many others. Bluetooth is very popular for local communications due to low power consumption, up to 100 meters range, and ease of use.